The present invention relates to a method of fixing a multilayer relief plate for flexographic printing to a printing cylinder.
It has been disclosed that multilayer relief plates for flexographic printing can be fixed to metal cylinders of printing presses using double sided adhesive sheets (cf. for example DE-A-No. 2,215,090 and GB-A-No. 1,366,769). Adhesive sheets of this type range in general from 100 to 500 .mu.m in thickness, so that tolerances are likely to be as high as 50 .mu.m, sufficient to prevent a clean impression.
Using such a double sided adhesive sheet a relief printing plate is generally mounted by first adhesively bonding one side of the adhesive sheet to the metal cylinder and then, by hand, placing and fixing the flexographic printing plate on the free adhesive surface to a high accuracy of register, which can be rather time-consuming.
In disassembly, the relief printing plate is peeled off the cylinder and stored for reuse, if required, when it will again be attached to a metal cylinder fitted with double sided adhesive sheet. After use the adhesive sheets are generally not reusable, and the cylinder needs to be cleaned of any still adherent adhesive. Since in disassembly, the forces required for peeling the printing plate off the adhesive sheet are fairly high, there is a danger that in the course of disassembly the printing plate will be damaged or destroyed by creases in the stabilizing layer (=inter-layer Z).
It is an object of the present invention to avoid the disadvantages described above and to present a method of fixing a multilayer relief plate to a printing cylinder without having to use the hitherto customary double sided adhesive sheet mounted on the cylinder, on the one hand, while making it possible to print within tolerances of &lt;.+-.10 .mu.m, on the other. In addition, satisfactory removal of the printing plate from the printing cylinder should require minimal force, not damage the plate or destroy the bond between adhesive layer and printing plate and leave behind no residue of printing plate or soiling on the printing cylinder.
We have found that, suprisingly, this object is achieved by applying a layer of contact adhesive having an adhesive force from 1 to 6 N/25 mm to the base layer of the multilayer relief printing plate.